1. Field of the Invention
The present invention relates to a printed wiring board which can suitably be used for a package substrate comprising a build-up multilayer wiring board for mounting an IC chip and a method of manufacturing the printed wiring board.
2. Discussion of the Background
Solder bumps are used for an electrical connection between a package substrate and an IC chip. Solder bumps are formed with the following steps.
(1) A step of printing flux on connection pads formed in a package substrate.
(2) A step of loading solder balls on the connection pads with flux printed thereon.
(3) A step of forming solder bumps out of solder balls by reflow.
An IC chip is placed on solder bumps after the solder bumps are formed on a package substrate and the solder bumps and the pads (terminals) on the IC chip are connected by reflow such that the IC chip is mounted on the package substrate. For the above-described step of loading solder balls on connection pads, the printing technology using concurrently a ball arrangement mask and a squeegee is shown in Japanese Unexamined Patent Application Publication No. 2001-267731, the entire content of which is incorporated herein by reference.